The invention relates to a sterile connector for containers which contain medicinal liquids, in particular liquids used in enteral feeding.
The packaging of sensitive products requires containers with very effective barrier characteristics, since otherwise there would be a risk of undesired reactions of oxygen with the product contained therein. Glass or metal containers have very satisfactory barrier characteristics. On the other hand, plastic containers are more problematic when used for the storage of sensitive contents.
Conventional plastic containers used for holding enteral nutrient solutions are comprised of laminated film that are sufficiently tight with respect to diffusion. Nevertheless, there is the disadvantage that the connector (port) that is generally made of polyolefins, in particular polypropylene, of the conventional film bag is permeable to certain gases. Therefore there is the risk of undesired reactions of the contents with oxygen. Also, aromatic substances present in the contents may diffuse through the connector. In practice, a decrease in the vitamin C content over time has been demonstrated in the storage of nutrient solutions. Thus, the shelf life of the product is limited.
DE 297 06 159 proposes application of a barrier module in the form of a flexible plastic foil made of a material having adequate diffusion tightness to the underside of the connector facing the container. The barrier module creates a barrier layer between the container contents and the connector that prevents the passage of gases or at least substantially limits it.
In one preferred embodiment of the film bag described in DE 297 06 159 the film piece provided for the purpose of sealing the bottom part of the connector is a laminated foil known in the art and based on a gas-tight metallic foil material with a coating of plastic material that can be bonded to the connector. The disadvantage is that said foils are not pure grade. Bonded connectors using EVOH foil are also known in the art. The use of EVOH as a barrier material is, however, disadvantageous inasmuch as the exposed cut edges of the foil piece are very sensitive, since the foil is cut or punched from a flat foil band that is cut into strips. Thus, it has been demonstrated that at the exposed cut edges increased discoloration and delamination occur after temperature and moisture stressing, as occurs in the sterilization process. Furthermore direct interactions between the internally situated foil components and the product cannot be excluded.
A further disadvantage presented by the barrier module in the form of flexible foil pieces is that form-fit and force-fit connections are not possible. In this respect the available bonding techniques are limited.
In order to establish a satisfactory barrier the entire upper and/or lower side of the connector should be covered by the barrier module. This is, however, only possible in part with the foil bonding when welded beneath. It has been shown in practice that with a slight overlap of the welded foil piece, the foil piece can slit the bag foil situated perpendicular to it. Therefore, it is necessary to maintain sufficient edge clearance, for which reason the entire area of the upper and/or lower side of the connector cannot be covered. Particularly in the case of small structural components, this area consideration can no longer be ignored.
Furthermore, the bonding of the foil piece with the connector is relatively costly. The cost corresponds approximately to that of welding the connector into the collapsible film bag. In addition, loss of tightness or leakage could occur at the weld seams.
The purpose of the invention is to provide a sterile connector that assures a high degree of gas-tightness, is easy to handle, and can be manufactured economically in large numbers.
In the connector pursuant to the invention the barrier module is an injection molded piece with a core and an envelope. The core is comprised of a material that is substantially impermeable for certain gases, while the envelope is comprised of a material corresponding to that of the base body, such that the base body and the injection molded part can be bonded or welded to each other.
When the sterile connector is welded into a collapsible bag the bag material can be bonded both with the base body, which is comprised of a material that can be bonded with or welded to the foil, and bonded or welded with the barrier module, which is comprised of the same material as the base body. Thus, it is possible to seal the container connection almost completely gas-tight.
Based on the formal freedom in injection molding, various connection techniques are available for the fastening of the barrier module. The barrier module can be manufactured economically and with low tolerances in large quantities as an injection molded piece. This can be accomplished using conventional extruders that have two plasticizer groups. Using the extruder, first the sheath and then the core is injected into a tool cavity. This process is also known as sandwich (injection) molding or the co-injection molding process.
The advantage is that the sandwich structure of the barrier module injection molded in one piece is relatively robust. Exposed edges, as in the case of the EVOH foils, that can lead to delamination and discoloration because of high temperatures and humidities, as occur in sterilization, do not occur in the barrier module.
In a preferred embodiment of the invention, the barrier module is welded onto the base body.
In a further preferred embodiment of the invention, the barrier module and the base body are bonded together by form-fit and/or force-fit methods. Thus, for example, the barrier module can be fastened to the base body using a snap or clamp-connection.
Also possible are one-piece component structures of base body and barrier module. Base body and barrier module can, for example, be held together by foil hinges so that said parts can be folded together and firmly bonded together after injection molding.
The barrier module preferably forms a puncturable membrane for closure of the passage into the connector that can be punctured by using a spike.
In order to facilitate the puncturing using the spike, the barrier module in the region of the passage is provided with an appropriate vulnerable area.
In a preferred embodiment the barrier module is a plate that covers the lower and/or upper side of the base body.
In another preferred embodiment the barrier module is fastened moveably to the base body in an intermediate position between a position closing the passage and a position opening the passage. Thus the barrier module simultaneously forms a seal or obturation that is actuated by the connection spike (33). For the purpose of significantly enhancing the gas barrier the barrier module preferably exhibits an oxygen barrier smaller than 1 cm3/m2d bar. The material comprising the essentially diffusion-tight core of the barrier module is preferably EVOH (ethylene vinyl alcohol copolymer) or PA (polyamide). The envelope of the barrier module is preferably comprised of polypropylene such that conventional bag foils, which present a seal layer on their inside made of the same material, can be easily welded with the barrier module. The parts so welded with each other exhibit a higher melting point than the sterilization temperature and can thus be sterilized in the autoclave.
The connector pursuant to the invention can be used in medical packaging units of the most varied forms. A preferred area of application is with a medical solution or medicinal liquid, in particular a collapsible bag filled with a solution or liquid for enteral feeding.